The cutting sharpness of chopping blades is decisive for the quality of the chopping material and the energy consumption of the chopper. The sharpness of blades is now determined primarily subjectively, above all by visual inspection of the chopping blades or by examining the quality of the chopping material. As in all visual evaluations, the experiences of the operating persons are essential.
The blades are poorly accessible. The chopper is stopped for inspection. The covers are removed. The blades are either immediately sharpened, as a result of evaluation, or only after subsequent inspections. Not only is the evaluation subjective, but the inspection point in time is also invariably subjective and therefore random, despite all experience. The inspections can only be conducted at larger time intervals because of the expense. The sharpening point in time cannot be optimally established in this procedure.
In many choppers, automatic sharpening and adjustment devices are now incorporated for the counterblades for immediate sharpening. With reliable determination of blade sharpness during chopping, the optimal point in time of sharpening could be determined more precisely and the downtime for sharpening reduced. Assembly work in the field and the risk of injury would be eliminated.
Some solutions for determination of blade sharpness of choppers during chopping are known. Generally, the power or moment of the chopper drive could be measured and the cutting forces determined from this. The moment, however, is not only dependent on blade sharpness, but also on throughput. This method is therefore too imprecise.
According to DE 199 03 153, the cutting forces acting on the counterblades are determined. It is assumed that the cutting forces necessarily rise during wear and a threshold value can therefore be established as a gauge for the now no longer sufficient blade sharpness. The cutting forces (the loads acting on the counterblades) are measured in two directions, namely, in the direction of the harvested product stream and also across this direction. At least two measurement devices are therefore always necessary, which must be aligned relatively precisely to each other and to the counterblade.
DE 40 23 113 and DE 40 23 114 start from the fact that the cutting geometry changes as a function of wear and, because of this, different stress pulses are induced in an inductive sensor during a pass. Limited blade thickness, and even more limited blade thickness through geometry changes with wear, impose strict limits on measurement accuracy.
The task of the invention is to offer a method and arrangement for determination of the sharpness of chopper blades with which the point in time for sharpening of the blades can be reliably determined during chopping.